As the temperature in Sweden reaches a record-breaking 45°, all those who've failed to escape Linköping for the summer take shelter indoors, shocked and paralysed by the heat. Then a teenage girl is discovered naked and bleeding in a local park, and soon a second girl is found dead. Alarmed by the fact that the victims are the same age as her daughter, Detective Malin Fors works around the clock to capture the perpetrator. But every lead comes to nothing, and time isn't on Malin's side ...